Propeller blade



Sept. 8, 1936. E. F. TECHMER PROPELLER BLADE Filed May 15, 1934 Hi5 ATTORNEYS Patented Sept. 8, 1936 UNITED STATES 2,053,851 PROPELLER BLADE Ewald F. Techmer, Chicago, Ill., assignor, by

direct and mesne assignments, to William E.. Bucholz, Chicago, 111., as trustee Application May 15, 1934, Serial No. 725,778

8 Claims.

My invention relates to the propulsion of airand watercraft and fluids, and includes among its objects and advantages the provision of an improved propeller.

'More specifically, the propeller blade embodies a fluid converging area in association with a thrust area arranged in the path of the converging fluid stream, reacting with the fluid stream in such a manner as to greatly increase the tractive properties of the blade. In addition, the blade is constructed to eliminate fluid slippage in lines tangentto the axis of the rotation of the blade and direct that portion of the fluid media in which it is acting in lines parallel to the said axis.

' The construction is applicable to propeller blades of conventional design as to length of blade, blade area, and pitch, with the resultsthat the efficiency of such blades is greatly increased.

In the accompanying drawing:

Fig. l is a plan view of the thrust'face of a propeller blade embodying the invention;

Fig. 2 is an edge view of the propeller taken from the position indicated by lines 2-2 of Fig. 1;

Fig. 3 is a sectional view taken along the line 3-3 of Fig.1; c

Fig. 4 is a sectional view taken along the line 44 of Fig. 2;

Fig. 5 is a sectional view taken along the line 55 of Fig. 1;

Fig. 6 is a perspective view of a different propeller construction commonly defined as a fan blade; and

Fig. 7 is a perspective view illustrating a different form of blade of the type illustrated in Fig. 6.

In the embodiment selected to illustrate my invention, I provide a propeller I comprising a hub portion [2 and blades M. The blades may be of conventional design so far as length, width, and pitch angularity is concerned. However, the thrust face iii of the blade is provided with a curved groove l8 having its ends 20 terminating with the leading edge 22 of the blade, and widening gradually toward said edge. Referring to Figs. 1 and 5, the bottom of the groove has a uniform depth inwardly of its ends for a short distance and then climbs gently up to points 24, between which points the groove is of shallower and uniform depth to provide an elevated surface 26 of slightly less altitude than the thrust face l6, now represented by the forward thrust surface 28 and the rear thrust surface 30. I make the surface 26 slightly concave, which provides a gentle.

surface 26.

angularity leading up to the rear thrust surface 30.

In operation, the groove l8 functions with a converging action with respect to the air compressed within the groove, tending to directthe converging air stream toward an area on the thrust surface 30 intermediate the outer endof the blade and its axis of rotation; This area lies substantially within the region rearwardly of the The thrust surface IS, in being arranged in the. path of the converging air stream, reacts thereon with a propulsive effect that greatly increases the tractive efficiency of the blade.

The converging function incident to my blade construction eliminates the usual slipping of the air throughout the entire length of the blade toward its outer end, so that a more effective hold of the blade upon the air is attained. As suggested above, the groove l8 directs one air stream outwardly with respect to the blade, 2. second stream inwardly toward the axis of rotation, and a third stream passes transversely of the blade because of the forward thrust surface 28, all of which unite in a concentrated stream, against which the rear thrust surface 30 impinges. Thus, it is the impinging of the intermediate portion of the rear thrust surface against the concentrated air stream and the prevention of endwise slippage of air that produces the increased tractive efiiciency of the blade.

To the. end of further eliminating endwise slippage of the air toward the ends of the propeller with respect to the thrust surface 30, I provide an upturned area 32 having a curved configuration conforming generally to the groove I8, which area co-operates with the area indicated generally at 34 for converging air impinging against the rear thrust surface toward the intermediate region above mentioned.

In Fig. 6, I illustrate my invention in connection with a propeller blade, commonly defined as a fan, for producing air currents. In the illustration shown, each of the four blades 36 is provided with a groove 38 separating the blade into thrust surfaces 40 and 42. The groove 38 is comparable to the groove l8, in that it operates with a converging action directing fluid compressed thereagainst to a point intermediate the ends of the blade. Similarly, my invention is applicable to a blade of the type illustrated in Fig. 7, in which the longitudinal axis of the blade 44 operates in parallelism with the axis of rotation of the assembly, by providing the blade with a groove 46.

My invention, when incorporated in a fan structure, increases its efliciency for producing air currents in the same degree that the invention increases the tractive eflficiency of the propeller blade previously described.

Obviously, my invention is applicable to screw propellers for driving all forms of watercraft.

Without further elaboration, the foregoing will so fully explain my invention that others may, by applying current knowledge, readily adapt the same for use under various conditions of service.

I claim:

1. A propeller blade comprising two thrust surfaces separated by a low surface, said low surface being so constructed and arranged as to deflect air longitudinally of the blade and toward. a point located between its outer end and axis of rotation and transversely of the blade at said point, one of said thrust surfaces being arranged in impinging relation with the transversely deflected fluid stream.

2. A propeller blade comprising two thrust surfaces separated by a low surface, said low surface being so constructed and arranged as to deflect air longitudinally of the blade and toward a point located between its outer end and axis of rotation and transversely of the blade at said point, one of said thrust surfaces being arranged in impinging relation with the transversely deflected air stream, and means comprising a part of the blade so constructed and arranged as to perform a supplemental deflecting function.

3. In a propeller, a blade having a thrust face, and a surface offset with respect to the thrust face so constructed and arranged as to deflect fluid compressed thereagainst in opposite directions longitudinally of the blade and transversely thereof at a point between the ends of the blade, the remaining surface of the thrust face being arranged to react against said transversely deflected fluid.

4. In a propeller blade, a 'face having means to deflect air compressed thereagainst in different directions, a thrust surface directing air at an angle substantially bisecting the angle between the first two air streams, and a thrust surface arranged in impinging relation with the three air streams, to react upon the same.

5. In a blade of the type described, a thrust face having two common thrust surfaces, a curved fluid directing surface separating said two common thrust surfaces, said fluid directing surface having a plurality of surfaces arranged at different altitudes with respect to the two thrust surfaces, said fluid directing surface being so constructed and arranged as to direct a concentrated fluid stream upon a limited area of one of said thrust surfaces, the latter being arranged in impinging relation with said fluid stream, the other of said thrust surfaces directing a fluid stream into the said concentrate-d fluid stream.

6. In a blade of the type described, a thrust face having two common thrust surfaces, a curved fluid directing surface separating said two common thrust surfaces, said fluid directing surface having a plurality of surfaces arranged at dilferent altitudes with respect to the two thrust surfaces, said fluid directing surface being so constructed and arranged as to direct a concentrated fluid stream upon a limited area of one of said thrust surfaces, the latter being arranged in impinging relation with said fluid stream, the other of said thrust surfaces directing a fluid stream into the said concentrated fluid stream, and means comprising a part of the blade so constructed and arranged as to prevent endwise slipping of the fluid from its axis of rotation to its outer end.

7. In a fluid propulsive device, a thrust face provided with means for directing two fluid streams longitudinally of the blade in the direction of each other, a thrust surface directing a third fluid stream substantially at right angles to the first two fluid streams, and a thrust surface arranged in impinging relation with the three fluid streams.

8. A propeller blade comprising a thrust face having a surface shaped to deflect fluid longitudinally of the blade and transversely thereof .at a point between its end and the axis of rotation, said thrust face including another surface arranged in impinging relation with the fluid moving transversely of the blade.

EWALD F. TECHMER. 

